This application in general relates to a stone shield which may be used with a welded yoke in an air brake actuator.
In the prior art, air brake actuators incorporate a piston moveable within an air chamber to actuate a brake. The piston includes a piston rod which moves through an opening in the chamber housing, and which has a yoke threadably connected to one end of the piston rod. The yoke is attached to an actuation structure for a brake. The prior art has typically utilized a stone shield which has a bore that closely circumscribes the outer peripheral surface of the piston rod to ensure that debris, rocks, etc., do not enter the chamber housing between the opening and the outer peripheral surface of the piston rod. Such shields have proven quite beneficial. Typically, the piston rod and piston are placed within the chamber housing, and the piston rod is inserted through the stone shield. The yoke is then threaded to the end of the piston rod which extends through the opening.
In another prior brake actuator, a yoke is welded to the piston rod. The use of a welded yoke reduces manufacturing costs, provides a more secure connection between the yoke and the piston rod, and simplifies the attachment of the brake actuator to the brake. A piston incorporating a yoke welded to the piston rod cannot be utilized with a stone shield, however, since the yoke has a larger diameter than the piston rod. The yoke thus cannot pass through the bore in the stone shield, which must approximate the outer diameter of the piston rod. The other end of the piston rod is attached to the piston, which typically has an even greater diameter than the yoke. Thus, the prior art has not successfully incorporated stone shields and welded yokes into a single brake actuator assembly.